1. Field of the Invention
This invention relates to an improved magnetic storage member for use in a magnetic storage unit such as a magnetic disk unit, a magnetic drum unit or the like.
2. Description of the Related Art
Generally, recording and reproducing systems for magnetic storage units having magnetic heads for recording and reproducing (hereinafter referred to as "head" for simplicity) and magnetic storage member are as follows. For instance, one of the systems relates to a contact-start-stop system (hereinafter referred to as "CSS" for simplicity). In the CSS system, at the start of operation, a head is brought into contact with the surface of a magnetic storage member and then the magnetic storage member is rotated at a given speed to thereby provide a spacing due to an air layer created between the head and the surface of the magnetic storage member, thereby enabling the recording and reproducing operations. In this system, at the end of operation, rotation of the magnetic storage member stops in a state where the head and the magnetic storage member are maintained in frictional contact with each other in the same manner as in the start of operation. Frictional power created between the head and the magnetic storage member, which are maintained in such frictional contact, causes the head and the magnetic storage member to wear out and, in the end, damages the head and a magnetic medium.
Furthermore, in the state of frictional contact as mentioned above, slight change in position of the head makes load added to the head uniform, whereby the surfaces of the head and magnetic storage member are in some cases damaged. In addition, when the head and the storage member come in contact with each other for long time, the head and the magnetic storage member are adsorbed to each other and thus it is hard to separate them from each other.
In order to prevent the magnetic storage member from being destroyed and adsorbed by contact and sliding with the head, the surface of the magnetic storage member (i.e. a protective film) has been coated with a lubricant, such as perfluoropolyether or the like, as referred to in Japanese Unexamined Patent Publication No. 52-49805. The publication describes perfluoropolyether having the following formula. ##STR1##
In addition, U.S. Pat. No. 4,696,845 discloses perfluoroalkyl compounds having a functional group such as --COOH, --CH.sub.2 OH or --COOCH.sub.3, and B. Bhushan, "Tribology and Mechanics of Magnetic Storage Devices", p. 641, Springer-Verlag New York Inc. (1990) describes a compound with the following piperonyl end group. ##STR2##
The above-mentioned functional groups have inorganic characters of 150, 100, 60 and 15, respectively.
However, the lubricants having the above-mentioned functional groups have weak adsorbability to the protective film and are removed from the surface of the protective film by repetition of the sliding with the head or a number of CSS's, or by the centrifugal force caused due to the rotation of the magnetic storage member such as the magnetic disk, and thus it is impossible to prevent the magnetic storage member from being damaged. In addition, the lubricant thus removed is thickly localized on and adsorbed to the contact sliding surface between the magnetic storage member and the head and thus it is hard to separate the storage member and the head from each other.